1. Field of the Invention
The present invention relates to a sheet separation member cooperating with a sheet feed roller to separate and feed sheets of paper one by one in an image forming apparatus such as a printer, a copying machine or a facsimile, and a sheet supply device including the sheet separation member.
2. Description of the Related Art
As this type of device, for example, as shown in FIGS. 17A and 17B, there is heretofore known a device configured to have a sheet separation portion 92 disposed to come into contact with lower end surfaces of sheets of paper 90 so that only an uppermost one of the sheets of paper 90 is separated by a frictional force between the sheet separation portion 92 and the lower end surfaces of the sheets of paper 90 (e.g. see JP-A-2002-137838).
In the conventional device, a separation portion supporting portion 93 is formed to support the sheet separation portion 92 by means of two support portions 93a and 93b each having a protrusive upper section in a longitudinal direction. Incidentally, a gap 93c is formed between the sheet separation portion 92 and the separation portion supporting portion 93 so as to give flexibility to the sheet separation portion 92.
The sheet separation portion 92 is made of a rubber material such as polyurethane. The sheet separation portion 92 has a convex end surface substantially fit to the shape of an end surface of a holder portion 91 disposed on the upper portion of the sheet separation portion 92. As shown in FIGS. 18A-18C, a protrusive portion 92a is formed in the sheet separation portion 92. The protrusive portion 92a is configured to always protrude from a long hole of the holder 91 made of metal. The long hole is formed so as to extend in a sheet stacking direction.
The height of the protrusive portion 92a is set so that the protrusive portion 92a protrudes from the long hole of the holder portion 91 by a predetermined amount. The lower edges of the sheets of paper 90 stored in a sheet storage portion are brought into contact with the upper surface of the protrusive portion 92a. 
Fine irregularities 92b are formed in the upper surface of the protrusive portion 92a. The fine irregularities 92b act to increase the frictional force generated between the sheet separation portion 92 and the lower edges of the sheets of paper 90.
The conventional device is configured in this manner so that the sheets of paper 90 are separated one by one by the frictional force of the rubber material and the action of the fine irregularities 92b to increase the frictional force and in accordance with the balance with a sheet feed force of the sheet feed roller.